A new design strategy for efficient electro-optic single-component organic crystals

A new, theoretically-derived synthetic concept for designing geometrically optimized, single-component organic crystals for the electro-optic effect, is presented. The idea relies on the mechanism responsible for the spontaneous evolution of polarity in channel-type inclusion compounds consisting of non-polar hosts. Single, elongated, rod-like molecular structures which incorporate both a strongly hyperpolarizable core and peripheral, non-polariable R-groups, may mimic the two-component structures of the polar inclusion compounds. In both systems, the energy difference in the lateral directions between antiparallel and parallel alignment of the active molecules is assumed to be approximately zero, and terminal functional group interactions along the direction of alignment are responsible for polarity evolution. By choosing molecules in which the direction of the largest hyperpolarizability is common with the geometric long axis, then efficient crystals for the linear electro-optic effect are envisaged. (C) 1999 Elsevier Science Ltd.